The present invention relates to a ink jet system printer of the charge amplitude controlling type and, more particularly, to an ink jet system printer of the charge amplitude controlling type which can print different size characters without deteriorating print quality.
Generally, in an ink jet system printer of the charge amplitude controlling type, a stream of ink droplets having a given frequency is emitted from a nozzle toward a record receiving paper and each ink droplet is charged to a desired amplitude in accordance with a video signal through the use of a charging electrode. Each ink droplet is deflected in the vertical direction as it passes through a fixed high voltage field established by a pair of deflection plates in accordance with the charge amplitude carried thereon and deposited on the record receiving paper. The nozzle is carried on a carriage which is driven to travel in the horizontal direction at a fixed speed during print operation, whereby printing is performed in a dot matrix fashion.
When the gain of the video signal is increased and the velocity of the travelling carriage is increased, a size of the printed character is enlarged. Contrarily, when the gain of the video signal is decreased and the velocity of the travelling carriage is decreased, the size of the printed character becomes smaller.
When the character size is varied without varying the size of the ink droplets, dot density will vary. This will deteriorate print quality.